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counting and probability intermediate
Problem
A poll shows that of all voters approve of the mayor's work. On three separate occasions a pollster selects a voter at random. What is the probability that on exactly one of these three occasions the voter approves of the mayor's work?
(A)
(B)
(C)
(D)
Solution
Letting Y stand for a voter who approved of the work, and N stand for a person who didn't approve of the work, the pollster could select responses in different ways: . The probability of each of these is . Thus, the answer is
Final answer
B